At present, various devices are used for drilling holes in the ground (cf. SU, A, No. 239, 132), each device comprises a body, a drive for moving the device, a base member screwed to the body. Used as a drive for moving the device are various mechanisms including an impact type pneumatic mechanism whose striker moves in space under pressure of a working agent supplied through a distributing mechanism and a hose held in the body in the preset position with the aid of the base member, a nut, for example.
The main disadvantage of such devices is characterized in that in operation the base member gets self-unscrewed under action of impact and vibration loads from the impact mechanism and due to friction of the base member side surface against the ground. As a result, the base member may be lost or tightness of the impact mechanism may be disturbed.
There are also known similar in design devices for drilling holes in the ground (for example, "Reversible Air Drift -4603A", 1986, Kiev, "Reklama", page 6, FIGS. 2, 3) in which a means for locking the base member relative to the body in order to protect the base member from self-unscrewing in the process of operation is made in the form of conical sections located both on the base member and the body. However, such a design of the locking means is not reliable. In the main the explanation consists in that due to the vibration and impact effect of the impact mechanism on the base member and as a result of friction of the base member side surface against the ground, the base member may be either self-unscrewed or screwed into the body. In the latter case the body may be broken in the point of conical joint or the base member may get stuck which will upset the operation of the whole device and hinder its maintenance.